The present invention relates to fan motors, and in particular, to a method of cooling fan motors.
A fan motor includes a stator and a rotor. Heat generated by fan motor operation is traditionally controlled by drawing air from outside the motor to cool the internal components. One method for controlling generated heat is by drawing air through a hollow core shaft to dissipate heat from the shaft to the passing air. Another method draws fresh air from outside the motor and pushes the air through the rotor stator gap. In an additional method, air is drawn through holes in the motor rotor laminations to dissipate heat. Increases in loads and desired power increases heat produced by the motor and therefore require improved methods and structures for removing heat.
Totally enclosed high power induction or permanent magnet motors used in aircraft fan applications are internal convection cooled. Due to higher power dissipated in new generation of such motors, cooling of the rotor is often challenging, resulting in use of expensive copper rotors, or use of hollow shafts with expensive brazed heat exchangers for cooling such rotors.